1. Field of the Invention
The field of art to which this invention pertains is solid-bed adsorptive separation. More specifically, the invention relates to an improved adsorbent suitable for use in a process for separating a component from a mixture comprising an aqueous solution of a mixture of different components.
2. DESCRIPTION OF THE PRIOR ART
It is known in the separation art that certain crystalline aluminosilicates referred to as zeolites can be used in the separation of a component from an aqueous solution of a mixture of different components. For example, adsorbents comprising crystalline aluminosilicate are used in the method described in U.S. Pat. No. 4,014,711 to separate fructose from a mixture of sugars in aqueous solution including fructose and glucose.
It is also known that crystalline aluminosilicate or zeolites are used in adsorption processing in the form of agglomerates having high physical strength and attrition resistance. Methods for forming the crystalline powders into such agglomerates include the addition of an inorganic binder, generally a clay comprising silicon dioxide and aluminum dioxide, to the high purity zeolite powder in wet mixture. The blended clay zeolite mixture is extruded into cylindrical type pellets or formed into beads which are subsequently calcined in order to convert the clay to an amorphous binder of considerable mechanical strength. As binders, clays of the kaolin type are generally used.
Zeolite crystal has long been known to have the property of gradually disintegrating as a result of continuous contact with water. It may be related to the surface migration and interaction between the charges of ions on the zeolite surface and in solution. In any event, the zeolite disintegration has been observed as a silicon presence or contamination in the solution in contact with the zeolite.
We have discovered an improved zeolite adsorbent and an improvement to an aqueous separation process which minimizes the disintegration of the zeolite and silicon contamination of the product.